DIFFRACTION OPTICAL ELEMENT AND EXPOSURE DEVICE INCLUDING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a diffraction grating which can produce a stabilized high resolution optical image.SOLUTION: The diffraction grating element is used in the illumination optical system of an exposure device in which a mask is irradiated with the light emitted from a light source through an illumination optical system, and a pattern on the mask is projected for exposure onto an exposed substrate through a projection optical system. In the intensity distribution of an illumination pattern diffracted by the diffraction grating element, a low diffraction efficiency region of low intensity distribution exists in the central part, and an annular high diffraction efficiency region is arranged concentrically on the outer periphery of the low diffraction efficiency region.